Stripping device



April 20 1955 R. H. MITCHELL 3,178,977

STRIPPING DEVICE Filed oct. 25, 1962 L ,1.1, HJ. L1: fw www wml,ahi/widen,

i; BY /Q ATTORNEY United States Patent O 3,178,977 STRIPPING DEVICERobert H. Mitchell, Winston-Salem, N.C., asslgnor to Western ElectricCompany, Incorporated, New York, N.Y., a corporation of New York FiledOct. 23, 1962, Ser. No. 232,405 Claims. (Cl. 83-145) This inventionrelates to a stripping device land more particularly to a selectivelypositionable stripper device to be used in conjunction with variousarrays of punches.

It is the conventional practice in the use of punch and die units todesign the stripper to fit the contour of the punch and die itself, and,therefore, make the stripper applicable to only that conguration forwhich it was designed. The production of a large quantity of a singlepart to be made on a punch and die, makes this design feasible. However,where small quantities of the product are anticipated, such as in a jobshop operation, the use of a punch and die made specifically for onepart, becomes uneconomical. To overcome this problem, tool designershave devised punch and die units which, by various means well known inthe industry, are capable of accepting an iniinite number of variationsin the pattern of punches and dies. These punch and die units arecommonly known as universal punch and die sets. Stripper arrangementsused on these universal punch and die sets normally consist of aspring-type or stationary stripper which is integrally made with orattached to each individual punch or die member. This design has thedisadvantages, among others, of limiting the closeness with which thepunches and dies can be arranged with respect to one another, and isinherently costly since na separate stripper is required for each punchand die set.

An object of this invention is to provide a new and improved strippingapparatus which can be used with an inlinite number of punch and diearrangements.

Another object of this invention is to provide a stripping device,including stripper bars, which may be randomly inserted into spacesbetween the paths of movement of the punches.

Still another object of this invention resides in the provision of awork stripping device for use with a universal punch and die setutilizing an infinite number of variations in the arrangement of punchesand dies wherein the stripper bars are randomly interspaced between thepunch members and are held in place by locking devices.

With these and'other objects in view, the present invention contemplatesa plurality of stripper bars to be placed randomly between the punchesof a die set, and a pair of channel members mounted on the face of andalong opposite edges of the die set, each of the channel members havingtransverse elongated slots formed in the channel sides to receive thestripper bars. Each channel member also has a pair of opposed guidewaysformed in the inner side walls of the channel into which are slidablymounted a plurality of locking members which are used for holding andlocking down the stripper bars.

A complete understanding of this invention may be had by reference tothe following detailed description when read in conjunction with theaccompanying drawings illustrating a preferred embodiment thereof,wherein:

FIG. l is a plan view of a die set utilizing a stripping device of thepresent invention which shows a random arrangement oi stripper barsarrayed in spaced between paths of movement of punch members;

FIG. 2 is a side elevation showing a transverse slot of a channel memberfor receiving the stripper bars;

FiG. 3 is a front elevation view of the stripper device mounted on a dieplate showing one channel member partially cut away, with a guideway inthe inner side walls which receives locking members; and

b FIG. 4 is a detailed view of one of the locking memers.

Referring in general to FIGS. 1 and 2, a die unit, generally indicatedby the reference numeral 11, is shown having a pair of channel members12 and 13 mounted on each side of a die bed 14. The channel members aremade up or machined to provide vertically extending sections 16 and -ahorizontal bottom section 17 (FIG. 2). The channel members 12 and 13 aresecured to the die bed 14 by bolts 19. Each of the side walls 16 has anelongated transverse slot 21 (FIG. 2) formed therein to receive stripperbars 22. Sliding within cruciform slots 23 (FIG. 3) formed in the walls16 of the channel members are a plurality of clamps, generally indicatedby the reference numeral 24. In cross section, the cruciform slotconsists of grooves formed in side walls 16 and a vertical section whichextends through members 12 and 13 and terminates at the slot 21. Screws18 brace and prevent distortion in slot 21, arising from pressure ofclamps 24 and withdrawal of punches 26 from a workpiece. Stripper bars22 are shown extending crosswise through transverse slots 21 in thechannel walls 16 and randomly into spaces between the paths of movementof individual punches 26 mounted on a punch platen 27.

As shown in FIG. 4, each clamp member 24 comprises a slide block 31which slides within side grooves of the cruciform slot 23 to positionthe clamp member. Each slide block 31 is internally threaded to receivea threaded portion of an Allen head bolt 33. An unthreaded end 34 of theAllen head bolt 33 is rotatably positioned within a recess formed in thetop of a cylindrical clamp block 36. Upon turning each bolt 33 withinthe slide block 31, the associated clamp block 36 is moved down to forceand lock each stripper bar 22 against the bottom 17 of the channelmembers 12 and 13.

In the use of this device, referring first to FIG. 3, a punch platen 27,sliding on liner pins 28 and having individual punch members 26extending therefrom,`is positioned Vover die plate 29. The punch platenis then brought down on the liner pins 28 so that the punch members areengaging the die plate 29. While the punch and die unit is in thisclosed position, the stripper bars are inserted into the elongatedtransverse slots 21 in the channel members 12 and 13 and through a slotformed in the bottom of clamp block 36 of the clamp member 24. Thestripper bars are then extended into the spaces between and in closeproximity to the punch members in a random fashion as shown in FIG. 1.Clamp block 36 is rotatably positioned on the unthreaded end of Allenbolt 33 so that the clamp blocks are rotatably adjustable to the randomangle of insertion of stripper bar 22 into the space between the punchmembers 2-6. The clamp members with stripper bars inserted therethroughare positioned along the channel members by sliding them along thecruciform slots 23 formed in channel members 12 and 13. It is necessaryto secure the stripper bars in their random positions to avoidsubsequent interference with the punch members during the punchingoperation. In order to secure the stripper bars in place afterpositioning of the stripper bars over the die plate, the clamp membersare tightened on the stripper bars by turning the Allen head bolt. Thisturning of the bolt 33 forces the internally threaded slide blocks 31,riding on the bolt 33, to push against the top of the cruciform slot 23to consequently force the clamp block 36 downwardly on the stripper bar22 which is pressed Vagainst the channel bottom section 17.

From the foregoing description, it will be seen that adjustment of theposition of the stripper bars is a simple and fast operation. First theAllen head bolt is turned to loosen the clamp block 36 on the stripperbar and to loosen the slide block 31 in the cruciform slot 23.Subsemembers and the stripper bars held therebeneath are also movablelongitudinally in the cruciform slot formed in the channel members as `aresult of the freeing of slide block 31 by the loosening of the bolt 33.

In the operation of the die unit il, and after the stripper bars havebeen positioned as described in the foregoing description, the punchplaten of the press is brought to the top of its stroke. A workpiece 41such as thin metal or plastic sheet is then positioned on the die plate29 and under the stripper bars 22. The punch platen is then brought downto commence the punching operation. The punch members penetrate theworkpiece and travel into the die openings of the die plate 29. Thepunch platen then begins to travel upwardly removing the punch membersfrom the workpiece. The stripper bars 22 which are positioned close tothe punches, engage the workpiece v il at this point and strip it fromthe punch to prevent the workpiece from clinging to the punch members asthe punch platen is brought to the top of its stroke. With the closepositioning of the bars to the path of movement of the punches, thepunches may be withdrawn from the sheet 41 without any tendency to tearor deform the sheet about one punched holes.

It is to be understood that the above-described arrangements are simplyillustrative of the application of the principles of this invention.Numerous other arrangements may be readily devised by those skilled inthe art which will embody the principles of the invention and fallwithin the spirit and scope thereof.

What is claimed is:

l. A stripping device to be used in a multiple punch and die unitcomprising,

a stripper bar,

a member mounted on one side of the die andrprovided with a slotextending therethrough to receive the stripper bar for longitudinal,transverse and angular movement in a horizontal plane between thepunches, and

a locking device slidably mounted on the member and projecting into theslot for locking the stripper bar in any or" a variety of longitudinal,transverse, and anguiar positions adjacent to the path of movement ofthe punch to hold a workpiece on the die upon removal of the punch fromthe workpiece.

2. A Work stripping device used in conjunction with a plurality ofpunches and a die member comprising,

a channel member mounted on one side of the die membei having a pair ofaligned transverse slots formed in the sides and extending therethrough,

stripper bars interspaced and randomly extending through said slots forlongitudinal, transverse, and angular movement in a horizontal planebetween the punches, and

locking devices slidably mounted in the channel member for locking thestripper bars in any of a variety t of longitudinal, transverse, andangular positions to engage the work during a punching operation.

3. In a workpiece stripper to be used with a universal punch and dieunit having a plurality of punches,

a plurality of elongated stripper bars placed in random angularpositions between the punches,

a pair of oppositely disposed channel members mounted on opposed sidesof the die and each having transverse slots formed in each wall toreceive the stripper bars for longitudinal, transverse, and angularmovement therethrough, and

locking devices slidably mounted in the channel members having dependingrotatable ends for engaging and locking the stripper bars in said randompositions to hold the workpiece in place.

4. In a hold-down device for use in punch and die apparatus wherein laplurality of punches are randomly mounted in a ram that is reciprocatedinto and out of a die mounted on a bed,

a pair of channel members mounted on the face of and along oppositeedges of the bed, each of said channel members having Itransverseelongated slots formed in the channel sides,

a plurality of stripper bars extendingl through said transverse slotsand into the spaces between the paths of movement of said punches forlongitudinal, transverse, and angular movement therebetween,

each of said channel members having a pair of opposed guideways formedin the inner side walls, and

a plurality of locking members having sections slidably mounted in theguideways for holding the stripper bars in any of a variety oflongitudinal, transverse, and angular positions.

5. In a work stripping device for use in a multiple punch and die unithaving a plurality of punches and a die,

two pairs of parallel plates mounted on the face of and along oppositeedges of the die unit, each of said parallel plates having an elongatedhorizontal slot formed therein, and having oppositely disposed andhorizontally extending grooves formed in their inner sides,

a plurality of stripper bars extending through the elongated slots forlongitudinal, transverse, and angular movement into spaces between theextending and randomly positioned punches when the punches arepositioned within the die, and

a plurality of clamp members having rotatably mounted depending ends forholding the stripper bars in a variety of longitudinal, transverse, andangular positions and having lugs slidably supporting the clamp membersinV the oppositely disposed grooves of the parallel plates forselectively positioning the depending ends in engagement with thestripper bars.

References Cited by the 'Examiner UNITED STATES PATENTS 475,549 5/ 92Firnstein 83-146 1,383,673 7/21 Thomas 83-145 1,500,263 7/24 Perrault83-146 1,646,851 l0/27 Campbell 83-146 ANDREWR. JUHASZ, PrimaryExaminer. HUNTER C. BOURNE, JR., Examiner.

1. A STRIPPING DEVICE TO BE USED IN A MULTIPLE PUNCH AND DIE UNITCOMPRISING, A STRIPPER BAR, A MEMBER MOUNTED ON ONE SIDE OF THE DIE ANDPROVIDED WITH A SLOT EXTENDING THERETHROUGH TO RECEIVE THE STRIPPER BARFOR LONGITUDINAL, TRANSVERSE AND ANGULAR MOVEMENT IN A HORIZONTAL PLANEBETWEEN THE PUNCHES, AND A LOCKING DEVICE SLIDABLY MOUNTED ON THE MEMBERAND PROJECTING INTO THE SLOT FOR LOCKING THE STRIPPER BAR IN ANY OF AVARIETY OF LONGITUDINAL, TRANSVERSE, AND ANGULAR POSITIONS ADJACENT TOTHE PATH OF MOVEMENT OF THE PUNCH TO HOLD A WORKPIECE ON THE DIE UPONREMOVAL OF THE PUNCH FROM THE WORKPIECE.